1. Technical Field
The present disclosure relates to an array antenna device that irradiates radio waves.
2. Description of the Related Art
Examples of an array antenna device used for radio communication or radio positioning include an array antenna device having a microstrip configuration.
Japanese Patent No. 5091044 discloses an array antenna device in which a plurality of array elements are arranged, each of the array elements including a sub-feeding strip line connected to a main feeding strip line, a rectangular radiating element connected to a terminal end of the sub-feeding strip line, and a stub provided between the radiating element and the main feeding strip line.
According to the above-described conventional techniques of Japanese Patent No. 5091044, however, the control range of the radiation amount of the radio waves from the array element is small, which is approximately 30% to 40%, and it is thus difficult to suppress side lobes of the radio waves radiated from the array antenna device. Besides, according to the conventional techniques of Japanese Patent No. 5091044, the array element is large in size and when a configuration in which a plurality of array antenna devices are arranged in a short-length direction of a main feeding strip line is employed, spacings in the short-length direction increase and upsizing of the whole device may be caused. The increase in the spacings in the short-length direction may allow grating lobes to occur easily, and the rise in the side lobes may cause decrease in gain and when the array antenna device is used in a radar device, incorrect detection may be caused.